The present invention relates to an information transferring apparatus having a first-in first-out stack.
It is common that information processors such as minicomputers or microcomputers use first-in first-out (FIFO) stacks as a data buffer. For example, as shown in FIG. 1, a conventional information processor generally consists of a central processing unit 1, an input/output unit 2, a FIFO stack 3 for transferring the information from the central processing unit 1 to the input/output unit 2 and another FIFO stack 4 for transferring the information from the input/output unit 2 to the central processing unit 1. Generally, the information between the central processing unit and the input/output unit is bidirectionally transferred. However, in a conventional FIFO stack, the transfer direction of information is only one way. It is for this reason that two FIFO stacks have been required in the conventional information processor, as shown in FIG. 1. In this manner, the conventional information processor uses a couple of FIFO stacks; however, it is impossible to concurrently transfer the information in bidirection between the central processing unit 1 and the input/output unit 2. In other words, concurrent operation of the FIFO stacks 3 and 4 is impossible so that when one FIFO stack is operated, the other must stop its operation. Thus, the operation of the FIFO stacks is extremely inefficient.